Backing Up To External Hd With Virus/malware?

Hi. I'm going to follow the cleaning instructions in the Malware Specialist thread. It advises you to back up files, but won't that transfer any virus or malware on the computer to the device you're using to back up (external hard drive in my case)? If not, do I need to back up anything other than things like photos, documents, and music files? Thanks!

 

If you re-read what it says:
"Backup Important Data First - While in most cases, we do not have problems, we cannot guarantee that there will not be any. Thus it would be a very good idea for you to begin by backing up all important personal information before undertaking the act of malware removal. You can bypass this step at your own risk, but remember that we cannot guarantee what the result will be from trying to remove malware from your PC."

It is telling you to make the choice whether or not to back up 'important data' first that you wouldn't want to lose as part of the malware removal process. Data that if you lost it would cause you serious problems.
If you have such important data - eg documents or photos that are crucial to you and which you don't have stored anywhere else - save them to a USB pen drive or recordable DVD for safekeeping. That removable media can also be scanned for malware very easily.